Wisconsin keeps swinging. It swung in 2018, as it swung in 2016, as it swung in 2012, as it swung in 2010, as it swung in 2006.

But if Wisconsin’s battleground status seems undiminished, there are also signs the sands are shifting underfoot.

So many factors figured into the narrow defeat of GOP Gov. Scott Walker on Tuesday, among them a tsunami of Democratic votes in the blue bastions of Dane and Milwaukee counties.

But one with major implications for the future involved the suburban counties outside Milwaukee that have long been Walker’s political bedrock.

'Walker Country' faltered

Instead, they contributed to his undoing Tuesday, when they failed to give Walker the same spectacular margins he had won in the past.

Waukesha and Ozaukee counties, two of the state’s wealthiest, most-educated and most-Republican counties, “underperformed” for Walker on Tuesday. The governor, who won Waukesha County by 46 points in 2014, carried it by 34 this time. He won Ozaukee by 41 points in 2014 but by 27 in 2018. Nowhere in Wisconsin did Walker’s winning margins decline as much as it did in those two counties.

You could write it off as a blip, but for four things:

One, these places had always come through for Walker. They were Walker Country.

Two, they were the same GOP counties where Republican Donald Trump showed striking weakness in 2016 despite his statewide victory. Comparing the Trump vote in 2016 to Mitt Romney’s presidential vote in 2012, nowhere in Wisconsin did Trump lag further behind the Romney vote than in Ozaukee and Waukesha.

Three, these counties until 2016 had entirely resisted a national demographic trend in which suburban areas in northern metros have moved away from the Republican Party.

And four, the suburbs have been a minefield for the GOP under Trump and they cost the party its House majority Tuesday.

Wisconsin’s “WOW” counties — Waukesha, Ozaukee, Washington — are legendary for delivering turnouts and landslides that made them among the highest-performing Republican counties in swing-state America.

They aren’t about to turn blue, and they haven’t “abandoned” the GOP the way some suburban counties have in other states. But the Republican vote has now lagged there for two elections in a row.

In the U.S. Senate race, the decline in GOP support was especially sharp. Democratic U.S. Sen. Tammy Baldwin won 42 percent of the vote in Ozaukee after winning 33 percent six years ago. She won 38 percent in Waukesha County after winning 31 percent six years ago. Those are not numbers we’re used to seeing Democrats get in these places.

If they’re now losing some of their partisan character, if they are starting to go the way of big-city suburbs elsewhere, if Trump is helping to make them less Republican, that could change the political math in Wisconsin.

The migration of blue-collar voters

But so could a countervailing trend in Wisconsin: the migration of blue-collar voters, mainly men, toward the GOP, a pattern especially striking in parts of northern Wisconsin.

Here, too, the trend in the Walker vote Tuesday followed the trend in the Trump vote in 2016.

Many of the same rural Wisconsin counties that swung hardest for Trump in 2016 performed better, not worse, for Walker in 2018, counties like Adams and Sawyer and Juneau and Rusk and Price. The governor held his own in much of northern and central Wisconsin. He won the Wausau media market by a slightly bigger margin than he did in 2014.

But this was not a good trade for Walker on Tuesday — doing better in a basket of small counties while doing worse in more populous ones.

His fall-off in base counties like Waukesha was paired with staggering losses in Dane and Milwaukee counties. Milwaukee shook off its midterm turnout doldrums. Dane turnout was at 95 percent of its 2016 presidential turnout and gave Democrat Tony Evers more votes than it gave Hillary Clinton two years ago.

Walker lost this election in southern Wisconsin, in the two big media markets of Milwaukee (which he won by about 80,000 votes less than four years ago) and Madison (which he lost by about 60,000 votes more than 2014). That was the story Tuesday, part of a growing national gap between more densely populated and less densely populated places.

Both parties fighting trends

That trend leaves both parties with sometimes fatal flaws.

The GOP’s core weakness is that in statewide races it struggles to overcome growing deficits in population centers.

The Democrats’ core weakness is that its strength in urban areas and inner suburbs can leave the party stranded on geographic islands, disadvantaged in legislative and congressional districts that stretch across rural America.

If the GOP suburbs here grow less Republican and the rural areas grow more Republican, Wisconsin will lose some attributes that set it apart from other states.

But there is no real sign it is losing its essentially swingy or purple character.

If you thought it was trending blue under Barack Obama, then 2010, 2014 and 2016 disabused you of that notion.

If you thought it was turning red after Walker and Trump, then 2018 is an inconvenient truth.

Four giant election fights since 2000 have been decided by less than a percentage point (three for president, one for governor).